A magnetic memory, for example, a magnetic random access memory stores data in a magnetoresistive element. Moreover, the magnetoresistive element comprises a basic structure including, for example, a reference layer (a ferromagnetic layer) having a perpendicular and invariable magnetization, a storage layer (a ferromagnetic layer) having a perpendicular and variable magnetization, and a tunnel barrier layer (an insulating layer) between these layers.
Here, for example, when writing is performed by spin transfer, decreasing a value of a spin injection current required for magnetization reverse and preventing the reverse of written data can effectively be accomplished by returning, to an original state, a shift of a looped resistance (R)-magnetic field (H) curve (an RH curve) of the storage layer due to a stray magnetic field from the reference layer, i.e., by correcting the curve.
To correct this shift of the RH curve, a shift corrective layer (the ferromagnetic layer having an invariable magnetization) is used. This shift corrective layer is usually stacked on the reference layer in the magnetoresistive element of a top pin type (a structure in which the reference layer is disposed on the storage layer), to cancel the stray magnetic field applied to the storage layer by a corrective magnetic field.
However, when the magnetoresistive element is made to be finer, it is difficult for the shift corrective layer to correct the shift of the RH curve of the storage layer. This is because when a planar size of the reference layer decreases in accordance with the fineness, the stray magnetic field from the reference layer at the position of the storage layer increases, and on the other hand, the shift corrective layer is away from the storage layer as much as a thickness of the reference layer, and hence the corrective magnetic field from the shift corrective layer at the position of the storage layer becomes smaller than the stray magnetic field from the reference layer.
Therefore, on the assumption that the magnetoresistive element is made to be finer, for the purpose of canceling the stray magnetic field applied to the storage layer by the corrective magnetic field from the shift corrective layer, it is necessary to take measures such as decreasing a saturated magnetization of the reference layer to decrease the stray magnetic field, and making the reference layer thinner to increase the corrective magnetic field.
On the other hand, perpendicular magnetic anisotropic energy has to be increased so that the reference layer keeps the perpendicular magnetization. For this purpose, the reference layer needs to be thick to a certain degree, and hence it is difficult to cancel the stray magnetic field by forming the thin reference layer. That is, the saturated magnetization of the reference layer is preferably decreased so that the corrective magnetic field from the shift corrective layer cancels the stray magnetic field applied to the storage layer.
However, when the saturated magnetization of the reference layer is decreased, it is difficult to select a material constituting the reference layer, to establish process conditions, or the like.